A variety of adverse knee conditions are prevalent among the patient population including a variety of knee injuries and osteoarthritis (OA). The nature of knee injuries varies widely including injury to ligaments, bone, meniscus and most importantly the articular or gliding cartilage of the joint surface. Although the purpose of knee surgery is to improve the function of the joint, it too creates an insult in the process. Therefore following injury, surgery or disease like osteoarthritis a rehabilitation protocol and process are instituted to provide optimal recovery. Just as in surgery, rehabilitation uses methods and devices to accomplish restoration of function and quality of life. As in surgery there are precise protocols and order of interventions to achieve an optimal result. The goals of rehabilitation are typically to restore motion, increase flexibility of such a knee and optimize muscle strength while protecting the articular surfaces. Rehabilitation often involves stretching exercises and workouts with weights. Both are often performed with traditional gym equipment, which is not particularly tailored to injuries of the knee. For example, weight machines and floor stretches may increase muscle and add flexibility while not addressing the lack of knee extension, the medial or lateral capsular and ligamentous contracture so essential to optimal rehabilitation and recovery. In addition, the protection of injured joint surfaces so common to injury, surgery and disease are often excluded from the rehabilitation process.
U.S. Pat. No. 5,687,742 provides a knee extension device that includes an L-shaped configuration having an elongated body portion and a lower leg support member. The subject's leg is positioned on the body member with the lower portion of the leg resting on the support member. Pressure is selectively applied to the leg to gradually force the knee towards a straight ended position. While this device may effectively straighten the knee it does not operate to strengthen the muscles, such as weakened quadriceps musculature. Accordingly, the subject must again workout with weights to regain strength to the surrounding muscles that affect the knee. Thus, the subject must use multiple devices or machines for treatment and risks irritation or injury to the knee when building muscle. As such, there remains a need to develop improved rehabilitation methods and devices that address all aspects of the process in an optimal order; correct the contractures, optimize the musculature, and protect the injured or disease joint surfaces during the process and during weight bearing of walking.
OA is the pathological condition manifested by articular cartilage softening, fissures, fragmentation and ultimately loss of the thickness of the gliding cartilage that covers the joint surface. This loss results in narrowing of the space between the bones of the knee with subsequent angulation of the tibia on the femur. Loss of cartilage predominately from the medial compartment results in bowleg deformity and similar loss of cartilage from only the lateral compartment results in knock-knee deformity. Persistence of either angulation deformity results in more force translated through the compromised compartment of the knee during walking causing progressive loss of articular cartilage. The progressive arthritis results in knee pain, limp, and loss of activities of daily living, sport and work. Over time there is secondary tightening of the soft tissues which becomes permanent and is known as a contracture. The contracture which may be medial, lateral or posterior may require surgical correction.
Those affected with such knee injuries or arthritis may have loss of ability to straighten their knee plus either bowleg or knock-knee will have difficulty walking due to the abnormal alignment. This will cause difficulty with activities of daily living, restriction from sports, and loss of work. Further, these conditions are often accompanied by weakened quadriceps musculature that further impedes function. This muscle weakness is propogated by the knee flexion deformity and the lack of use due to pain. The loss of muscle strength compounds the medical disability. Thus, in some instances treatment of such injuries or conditions may actually require a combined approach that addresses both the joint as well as the resulting weakening of the quadriceps muscle.
There are a variety of ways to accomplish correction of knee contracture, weakness of the quadriceps femoris muscles and symptoms of early arthritis of the knee such as bowleg or knock-knee deformity, including many cumbersome and expensive devices, health care provider implemented physical therapy and even surgery. However, each has significant drawbacks including inconvenience of availability, high costs and further medical risks to the patient.
Accordingly, there remains a need to develop non-surgical devices that are inexpensive and easy to use by those suffering from medical conditions affecting the knee. Further, there remains a need to develop such devices for the convenience of home therapy.